It is said that whether in terms of distance covered, number of endpoints generated or value invested, the most predominant transmission medium for communication networks worldwide is that of copper. This has resulted from the use of copper as a transmission medium in the earliest of large scale telephony networks. Although copper has now largely been superseded in trunk or distribution networks by the use of optical fibre, many access networks, such as the local loops of public switched telephone networks, continue to employ copper. Globally, it is estimated that many tens of millions of tons of copper are deployed in such access networks and that this transmission medium may account for roughly one-half or more of the assets of the typical network operator.
As a transmission or delivery medium in modern communication networks, copper presents the challenge that it provides a theoretical maximum information rate of only approximately 35 kbps to 56 kbps across public switched telephone networks. Many technologies have emerged to extract higher bandwidth data transmissions from the existing copper based networks, due to a market demand for the delivery on such networks of higher bandwidth applications such as digital video and high-speed Internet access. For instance, a number of digital subscriber line or loop (DSL) architectures have been introduced in the last decade, each providing differing combinations of upstream data rates, downstream data rates and ranges of operation. Collectively, this family of digital subscriber line architectures is sometimes referred to as xDSL and will be so referred to in this specification to denote all such digital subscriber line architectures.
The various xDSL architectures as introduced above cannot typically operate in ranges which exceed a few kilometers. For example, in high-speed digital subscriber loop (HDSL) technologies, data rates in the neighbourhood of 2 Mbps can be achieved by combining the capacity of two or three pairs. However, this is sustainable only over a distance of approximately 3 km. Using very high rate digital subscriber loop (VDSL) techniques, data rates as high as 23 Mbps in the downstream direction and 3 Mbps in the upstream direction can be attained, but only for distances in the neighbourhood of one kilometer at such rates.
In the context of telephony networks, various prior art solutions for controlling network traffic from the central office (“CO”) to the remote access terminals have been proposed.
One prior art solution for traffic flow management provides an “end-to-end” flow control implemented between the CO and the remote access terminals connected to an access network. In this prior art system, traffic flow control signals are passed between the remote access terminal and the CO in order to effect back pressure as necessary to moderate the traffic flow being directed to the remote access terminal down to a rate suitable for the remote terminal's established train rate, i.e. transmission rate. However, in such an end-to-end flow control system, the latency associated with passing control signals over a potential distance of many kilometers between the remote user terminal and the CO may be a significant problem.
There is therefore a need for an approach to controlling traffic flow directed to a remote node or device which intends to avoid some of the drawbacks identified above for prior art systems and methods.